1. Field of the Invention
The present invention relates generally to a method for automatically calibrating the printing of a lenticular image with respect to the lenticules of a lenticular medium, such as a lenticular sheet, in a device including an ink jet printer, a sensing device, and a processing unit.
2. Description of the Related Art
It is known to print a lenticular image on a sheet of material and then overlay a transparent lenticular sheet in order to achieve one of several special effects. Alternately, the lenticular image can be printed directly on the backside of a transparent lenticular sheet. The lenticular image comprises a series of interlaced image slices, wherein the slices are portions of two or more different source images. The lenticular sheet includes a plurality of semi-cylindrical lenses, or lenticules, arranged in parallel, and the image slices are aligned with the lenticules. The different special effects that can be obtained, for example, include a three-dimensional effect, motion of an object, morphing between two different images, and flipping between different images. For example, a lenticular image can be created by interlacing slices of source images that are different perspective views of an object. Viewing such a lenticular image through the lenticular sheet creates a three dimensional effect. Similarly, if a lenticular image is derived from interlacing source images of an object at sequential points in time, viewing the lenticular image through the lenticular sheet conveys an impression of motion as the position of the viewer changes with respect to the lenticular sheet.
Advances in ink jet printing have allowed lenticular images to be printed using ink jet printers. Achieving a desired lenticular effect depends on precisely printing the lenticular image such that the image slices are precisely aligned with respect to the lenticules of the lenticular medium. Lenticular sheets are generally available with lenticules at such resolutions as 60 lines per inch or 100 lines per inch. However, these given resolutions are generally nominal values, with the actual resolution of the sheet being within a specified range of the nominal value. Similarly, specifications for ink jet printers generally include a nominal printing resolution value, such as 600 dots per inch, with the actual resolution varying within a specified range.
A typical ink jet printer includes one or more printheads mounted on a carriage mechanism. The carriage mechanism is moveable in a lateral (or main printing) direction that is transverse to an advance direction of a print medium such as paper or a lenticular sheet. The printhead is moved in a series of passes across the print medium and during each pass, ink is selectively expelled from nozzles to form ink drops at corresponding ink drop placement locations in the image area of the print medium. Since the printhead moves in a direction transverse to the advance direction of the print medium, each ink ejecting nozzle passes in a linear manner over the print medium. A desired image is thus printed by the combination of lateral printing passes and longitudinal advances of the print medium. In some designs, the printhead is capable of bilateral operation, that is, it expels ink as it moves in a lateral direction across the paper both in a forward direction and in a reverse direction. In some designs the ink jet printer includes a black printhead for printing black ink and a three-color printhead including pens for printing cyan, yellow and magenta ink. Other designs may include separate printheads for each color of ink, or a different numbers of printheads. Further, the ink jet printer may include a printhead alignment sensor, such as described in U.S. Pat. No. 6,655,777, assigned to the assignee of the present invention. These printhead alignment sensors are used to sense the position of the ink drops expelled from the printheads.
Ink jet printers are often part of all-in-one (AIO) devices that typically also include a scanner and a fax module. Such devices can be configured as stand-alone devices or can be coupled to a personal computer or network.